Vehicle windshield wiper assemblies typically have a pair of wiper arms, which are swept outwardly and back inwardly in tandem between inner and outer limits that define what may be termed as a normal wipe pattern. Federal standards set guidelines for what the normal wipe pattern must be. The wiper arms are swept back and forth by a power source, generally an electric drive motor, that has a low and a high setting, or perhaps a continuously variable range of high and low settings. Usually, the driver's side wiper arm will be driven by the motor, while the passenger side wiper arm will be driven in tandem through a link mechanism. In general, the higher power settings will sweep the wiper arms back and forth at a higher speed. Consequently, the higher power settings will be chosen for heavier rains, that is, when the wetting of the windshield surface is greater, there being no reason to choose the higher power settings when the wetting is slight. The setting of the drive motor is not the only factor that determines the resultant angular speed of the wiper arms, however. The surface of the windshield presents more or less frictional resistance to the blade of the wiping arm, depending on whether it is tacky or well wetted. Therefore, a given power setting will generally produce higher resultant wiper arm speeds as the surface becomes wetter. The resistance of the windshield surface to having the blade wiped across it creates a consequent opposing reaction torque in the wiper arm, which, for any power setting, is generally greater for drier, more frictional windshield surface conditions. However, research involved in the development of the subject invention showed that the inertial tendency of the wiper arm to keep moving in the direction that it is sweeping becomes a very significant component of reaction torque as the limits of the wipe pattern are approached. The inertial effects can cause the peak reaction torque to reach a maximum for the extreme conditions of highest power setting and greatest windshield wetting, a maximum that can be significantly greater than the peak reaction torque for other conditions.